review team: john gray, usgs david newburn, umd-college ... lsrwsa rev… · in the reservoir, not...

Review Team:

Carl Friedrichs (Lead), VIMSTheo Dillaha, Virginia TechJohn Gray, USGSRobert Hirsch, USGSAndrew Miller, UMD-BaltimoreDavid Newburn, UMD-College ParkJames Pizzuto, Univ of DelawareLarry Sanford, UMCESJeremy Testa, UMCESGeorge Van Houtven, RTIPeter Wilcock, Johns Hopkins

STAC Report = 40 p., condensed from ~ 100 pages of individual reviews submitted by the team.

Available to all of STAC, to be publically released following USACE approval.

Source: USACE LSRWA Study Report

Motivation:

Motivation: Hirsch (2012)

Motivation (cont.):

Hirsch (2014)

*Jan’14 CBP Modeling Quarterly Review Meeting.]

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http://www.lowersusquehannariverkeeper.org

50 pages of comments submitted to FERC on 1/31/2014

Controversy:

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Presented to US Senate Committee on Environment & Public Works

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Controversy (cont.):

LSRWA Study Partners and Scope:

-- Lead: (i) U.S. Army Corps of Engineers (USACE) Baltimore District and (ii) Maryland Dept. of the Environment.

-- Additional members of LSRWAInteragency Team: (iii) U.S. Geological Survey, (iv) USACE’s Engineer Research and Development Center, (v) Susquehanna River Basin Commission, (vi) The Nature Conservancy, (vii) EPA Chesapeake Bay Program Office, and (viii) Maryland Department of Natural Resources (including the Maryland Geological Survey).

-- 3 years (2011 – 2014), $1.4 Million, 75% Federal/25% non-Federal cost-share.

-- Main report = 239 pages; Appendices = 1025 pages.

LSRWA Study purpose:

-- Analyze the movement of sediment and associated nutrient loads within the lower Susquehanna watershed through the series of hydroelectric dams (Safe Harbor, Holtwood, and Conowingo) located on the lower Susquehanna River to the upper Chesapeake Bay.

-- Including: (i) analyze hydrodynamic and sedimentation processes and interactions within the lower Susquehanna River watershed, (ii) consider strategies for sediment management, and (iii) assess cumulative impacts of future conditions and sediment management strategies on the upper Chesapeake Bay.

-- The need for this assessment is to understand how to better protect water quality, habitat and aquatic life in the lower Susquehanna River and Chesapeake Bay.

Boomer (2014) [at Mar 2014 STAC Meeting.]

“Why Request a STAC Review?

-- Fresh eyes to help identify gaps, opportunities… all especially important

given potential legal proceedings.

-- Opportunity to share state of the science”

Review Organizer, Kevin Sellner, Chesapeake Research Consortium – STAC Exec Sec

Review Team:

Carl Friedrichs (Lead), Virginia Institute of Marine Science – STACTheo Dillaha, Virginia TechJohn Gray, U.S. Geological SurveyRobert Hirsch, U.S. Geological Survey – STACAndrew Miller, University of Maryland, Baltimore Campus – STACDavid Newburn, Economics, University of Maryland, College Park – STACJames Pizzuto, University of DelawareLarry Sanford, University of Maryland Center for Environmental ScienceJeremy Testa, University of Maryland Center for Environmental ScienceGeorge Van Houtven, RTI InternationalPeter Wilcock, Johns Hopkins University

Expertise: resource economics, and watershed, riverine, and estuarine processes

Charge to review team from STAC Executive Secretary:

“You should focus your comments on the following *questions+, but you are encouraged to provide additional comment that would improve the analyses, report, or its recommendations.

Question 1: Does the main report clearly define the goals, strategies, and the results/conclusions of the study, and also present adequate background material at a level suitable for understanding by non-technical audiences?

Question 2: Are the alternative sediment management approaches clearly described and documented? Does this background material provide supporting evidence for the finding and conclusions of the study with regard to alternative sediment management approaches?

Question 3: Does the main report provide clear, supporting evidence for the results, findings, and conclusions of the study?

Question 4: Does the report adequately identify key uncertainties in the model applications which, with better information, could change the predicted outcomes of the alternative management scenarios evaluated in this study?

Question 5: Are the recommended follow-up evaluations and analyses (Section 9.1) complete and comprehensive as well as clearly stated to enable the next phase of work to continue under the Partnership’s Midpoint Assessment?

Question 6: Do the technical appendices provide the necessary documentation for the models and their applications in support of the study’s results, findings, and conclusions?”

General reaction of the review team to the LSRWA report

Overall positive:

-- The majority of the reviewers of the LSRWA report agree that its authors have done a commendable job in trying to address an extremely challenging set of issues.

-- Overall, the results of the study are reasonable, the major conclusions are important, and the report’s recommendations are by-and-large appropriate and productive.

-- The project was an enormous effort with multiple participants, and the authors did an impressive job bringing together a wide range of information to support their report.

General reaction of the review team to the LSRWA report (cont.)

But…

-- The science that needs to be done here is at the cutting edge of what sediment transport and water quality science has ever accomplished in the past.

-- Thus, there are no standard models and protocols for such a study, and the existing capabilities are understandably limited.”

-- Hence, it is not surprising that the review team identified many sections of the report that would benefit from revisions, corrections and/or additional analysis.

Question 1: Does the main report clearly define the goals and strategies of the study?

-- Goals are 50%/50% Sediments vs. Nutrients:

(LSWRA Report p.10): “the specific goals and objectives for the LSRWA effort were: 1. Generate and evaluate strategies to manage sediment and associated nutrient loads delivered to Chesapeake Bay… 2. Generate and evaluate strategies to manage sediment and associated nutrients available for transport during high-flow storm events to reduce impacts on Chesapeake Bay. 3. Determine the effects to Chesapeake Bay due to the loss of sedimentand associated nutrient storage within the reservoirs on the lower Susquehanna River.”

-- But the Purpose and Approach are ~80%/20% Sediments vs. Nutrients:

(LSWRA Exec. Summary p.ES-1): “The purpose of this assessment was to analyze the movement of sediment and associated nutrient loads within the lower Susquehanna watershed through the series of hydroelectric dams... This included analyzing hydrodynamic and sedimentation processes and interactions within the lower Susquehanna River watershed, considering strategies for sediment management, and assessing cumulative impacts of future conditions and sediment management strategies on the upper Chesapeake Bay.”

-- The review recommends that the “original goals” of the study (i.e., sediment management to extend the life of Conowingo Dam more than nutrient management to protect Chesapeake Bay water quality) be presented in the introduction followed by a fuller explanation of how and why the focus of the study evolved in time toward the impact of nutrients.


Watershed management of sediment costs 50 times as much as sediment bypassing. However, LSWRA study focused on cost of reducing amount of sediment from behind Conowingo Dam, NOT the cost of removing nutrients.


-- Where clearly defined as methods for reducing the cubic yards of total sediment present in the reservoir, the alternative sediment management approaches were found by the large majority of the reviewers to be well-documented, well-described, and comprehensive.

-- This review recommends that further caveats be included throughout the report to clarify that the dollar-based cost estimates regarding alternative sediment management approaches are specifically for reducing cubic yards of total sedimentin the reservoir, not for achieving broader goals regarding nutrient reductions.

-- The LSRWA report should also emphasize that further analysis would be required to appropriately rank the alternative strategies based on a more environmentally relevant total cost in terms of dollars per pound of nitrogen and/or phosphorus reduction.

Question 3 & 4: Does the main report provide clear, supporting evidence for the results, findings, and conclusions of the study? Does the report adequately identify key uncertainties in the model applications which, with better information, could change the predicted outcomes of the alternative management scenarios evaluated in this study?

Question 3 & 4: Does the main report provide clear, supporting evidence for the results, findings, and conclusions of the study? Does the report adequately identify key uncertainties in the model applications which, with better information, could change the predicted outcomes of the alternative management scenarios evaluated in this study?

General Uncertainty – Although the report lists and discusses sources of uncertainty, it expresses the expected confidence intervals on its model predictions less often. Ideally, ranges of uncertainty should be provided for all model predictions (rather than a specific number).

-- The review recommends the LSRWA report should more explicitly explain why confidence intervals on predictions are generally not provided.

Reduced deposition associated with reservoir infilling has been neglected – Net trapping efficiency is the sum of increases in average annual scour and decreases in average annual deposition. However, the simulations and calculations in the study only considered the increase in scour. This issue underlies a significant weakness in the report, which is that it focuses its inquiry on the impact of large, but infrequent, scour events rather on the total impact of the change in trapping efficiency of the reservoir system.

-- The review recommends that a discussion should be added to the report that clearly states that decreases in the average annual deposition in the reservoir in the absence of scour have not been considered.

-- The revised report should clearly state that the added transport of sediment-associated nutrients past Conowingo Dam due to decreased deposition may be as large as that due to increased scour.

Question 3 & 4 (cont.): Supporting evidence for the results, findings, and conclusions of the study/identification of key uncertainties?

Grain size effects within and exiting the reservoir were not sufficiently considered – It is reasonable to expect that the texture of the sediment behind the dam will continue to coarsen through successive scour events and deposition interludes. Nutrients associated with fine sediments, not with the total load of sediments, are the main water quality concerns.

-- The review recommends that the concept of dynamic equilibrium be clearly qualified in the report to indicate it does not yet apply to sediment grain size, and thus it does not yet fully apply to the flux of fine sediment or associated nutrients.

Limitations of HEC-RAS and AdH models were not made sufficiently clear – The HEC-RAS modeling effort was unsuccessful. The AdH model was not fully validated and was forced by boundary conditions outside the range of observations. AdH model has not, as yet, added substantial new understanding of the sediment dynamics of the reservoir.

-- This review recommends that the failure of the HEC-RAS model be reported more clearly and fully in the Chapter 4 of the main report.

-- This review also recommends that the limitations of the AdH application as described above be made much clearer in both Appendix B and the main report.

-- The review recommends that more of the observational data in the Appendices be incorporated into the main report, particularly those that bear on the time-varying sediment budget. This will make the report’s conclusions more convincing. Even if the fidelity of the models can be questioned, the observational data are compelling.

Question 5: Are the [main conclusions] and recommended follow-up evaluations and analyses (Section 9) complete and comprehensive as well as clearly stated to enable the next phase of work to continue under the Partnership’s Midpoint Assessment?

LSRWA Finding 1:

Present version: Conowingo Reservoir is essentially at full capacity; a state of dynamic equilibrium now exists. There has been a loss of loss of long-term sediment and associated nutrient trapping capacity.

Recommended rephrasing: The Conowingo Reservoir is essentially at full capacity and is no longer a long-term sink helping to prevent sediment-associated nutrients (primarily particulate phosphorus) from entering the Chesapeake Bay.

LSRWA Finding 2:

Present version: The loss of long-term sediment trapping capacity is causing impacts to the health of the Chesapeake Bay ecosystem.

Recommended rephrasing: Increases in particulate phosphorus loads entering the Bay as a result of the full reservoir are likely causing significant impacts to the health of the Chesapeake Bay ecosystem.

Question 5 (cont.): Are the [main conclusions] and recommended follow-up evaluations and analyses (Section 9) complete?

LSRWA Finding 3:

Present version: Sources upstream of Conowingo Dam deliver more sediment and nutrients, and therefore, have more impact on the upper Chesapeake Bay ecosystem, than do the scoured sediment and associated nutrients from the reservoir behind Conowingo Dam.

Recommended rephrasing: Sources of nutrients upstream of the Conowingo reservoir have far more impact on the Chesapeake Bay ecosystem than do the increases in nutrients caused by scour plus reduced deposition in the reservoir.

LSRWA Finding 4:

Present version: Managing sediment via large-scale dredging, bypassing and dam operational changes, by itself does not provide sufficient benefits to offset the upper Chesapeake Bay water quality impacts from the loss of longterm sediment trapping capacity.

Recommended rephrasing: Managing sediment via large-scale dredging, bypassing and/or operational changes are clearly not cost-effective ways to offset Chesapeake Bay water quality impacts from the loss of long-term trapping of sediment-associated nutrients.


LSRWA Recommendation 1:

Present version: Before 2017, quantify the full impact on Chesapeake Bay aquatic resources and water quality from the changed conditions in the lower Susquehanna River and reservoirs.

Recommended rephrasing: As soon as possible, follow-up studies should more fully quantify the impact on Chesapeake Bay water quality from increases in sediment-associated nutrients brought about by reservoir infilling.


Present version: U.S. EPA and Bay watershed jurisdictional partners should integrate findings from the LSRWA into their ongoing analyses and development of the seven watershed jurisdictions’ Phase III WIPs as part of Chesapeake Bay TMDL 2017 mid-point assessment.

Recommended rephrasing: There is no compelling reason to reduce sediment loads per se from the Susquehanna watershed to compensate for increased sediment passing out of the Conowingo reservoir. Nutrients are the main problem, not sediments.



Present version: Develop and implement management options that offset impacts to the upper Chesapeake Bay ecosystem from increased nutrient and sediment loads.

Recommended rephrasing: Additional particulate phosphorus load reductions from the Susquehanna watershed (beyond present WIPs) should be considered to compensate for changes to the Conowingo.


Present version: Commit to enhanced long-term monitoring and analysis of sediment and nutrient processes in the lower Susquehanna River system and upper Chesapeake Bay to promote adaptive management.

Recommended rephrasing: Commit to enhanced long-term monitoring and analysis of sediment and nutrient processes in the lower Susquehanna River system and upper Chesapeake Bay to promote adaptive management in response to improved scientific understanding.


Suggested Additional LSRWA Finding/Recommendation:

The negative impacts of sediment input to the Chesapeake Bay (relative to nutrients) are overstated by present TMDLs and are overemphasized in management priorities

-- TMDL requirements for sediment loads are most likely overly restrictive. The water quality simulations conducted as part of the LSRWA study further support the conclusion that sediment alone does not have as great an impact on Bay aquatic life and attainment of water quality standards as previously thought.

-- An underlying assumption at the start of the LSRWA study, and indeed of the CBP in general, is that all sediment is bad. However, some sediments are actually good, important components of the estuarine ecosystem (e.g., for sustaining wetlands and habitat).

-- Given the relatively minor impact of sediments in general (separate from their associated nutrients) to Bay water quality, it is especially clear that the additional sediments (separate from nutrients) associated with the filling of the Conowingo reservoir are particularly insignificant to overall Bay health.

-- The effectiveness of BMPs in reducing sediment loads to the Bay may be overstated by present TMDLs. This is ultimately a result of massive watershed storage of sediment.

-- Thus, the possibility that sediment BMPs may not lead to a major reduction in sediment coming from the upstream watershed needs to be considered as a real possibility in considering management actions.

review team: john gray, usgs david newburn, umd-college ... lsrwsa rev… · in the reservoir, not...

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